Welsh Conservative leader Andrew RT Davies could be facing a further damaging challenge to his authority as it emerged moves are being made to seriously dilute his responsibility over policy.

Senior party sources have told WalesOnline that serious consideration is being given to a system where the leadership would need to gain approval from the party membership, or the Welsh party’s management board, before policies were formally adopted.

Such a move, which could be attempted before the Welsh Tory Spring conference, if adopted could severely curtail Mr Davies’ independence in setting policy and deal a blow to his credibility as leader.

The proposal – which we understand has been floated in the party for some time – has gained traction in recent weeks due to the damaging fallout from a fissure running through the Assembly group, after Mr Davies sacked four members of the Shadow Cabinet who refused to vote with a Plaid Cymru amendment criticising the UK Government’s proposed model for using income tax-varying powers in Wales.

It followed a public spat between Mr Davies and Welsh Secretary David Jones over Mr Jones’ support for the so-called “lockstep” on proposed powers – a mechanism which would prevent Welsh Ministers varying individual bands of income tax, meaning they would have to cut or raise all three bands together.

Mr Davies is understood to be have been told to bring the four sacked Members – Monmouth AM and former Business and Enterprise Committee chairman Nick Ramsay, North Wales AM Antoinette Sandbach, Aberconwy AM Janet Finch-Saunders and South Wales East AM Mohammad Asghar – back into the Shadow Cabinet, in similar positions to what they had before, before the party conference next month.

The unity of the group is already under severe strain after one AM – Ms Sandbach – lodged a complaint with the board over the conduct of a colleague, Darren Millar, over alleged unreasonable pressure put on her to vote with Mr Davies’ position in the income tax vote.

The Welsh Board of the party is not believed to have discussed the membership policy proposal in board meetings, but senior figures have suggested it could emerge as an issue before the party’s conference in April amid growing concern of a gulf between the Assembly group and grassroots members. Such a move could see policies put to conference to vote on, or policies vetted by the Welsh management board.

Mr Davies standing with the board is already at a low ebb, with sources confirming last month that the fallout from the sackings resulted in unanimity among other board members against his handling of the crisis.

A senior Welsh Conservative source said: “I think this could be considered a nuclear option. But it is one that is probably going to be attempted, and possibly used, even if he [Mr Davies] brings the four AMs back or not. I think this could be on the cards, come what may.”

Sources said the process could be initiated by the Board itself, without the need for the party to go through the process of changing its constitution, although this is believed to be disputed by the leadership.

Jeff James, chairman of the Welsh Conservative Party, said: “Policy formulation has not been discussed by the Welsh Board. The Assembly group will continue to put forward exciting alternative ideas for Wales.”